This invention relates generally to the measurement of water levels and more specifically concerns apparatus for remotely measuring at many different selected locations on the surface of the earth the water status at those locations.
Prior techniques for monitoring water status use an individual instrument for each measurement type and require active instruments which include power supplies, recorders, transmitters and other in situ instrumentaion. Measurement activation or recording requires special interrogation and, in most instances, manned attendance.
The prior techniques for monitoring water status have many disadvantages. They require several different instruments to obtain measurements, they are not suitable for global, day-night, all-weather measurement systems, they are clostly and require expensive upkeep and calibration, they require complex equipment and high technical skills for utilization, and they do not provide daily multiple measurement data without considerable difficulty.
It is therefore the primary object of this invention to provide simple, inexpensive apparatus for obtaining measurements of water status at many selected locations on the surface of the earth.
Another object of this invention is to provide apparatus for obtaining measurements of water status at selected locations on the surface of the earth in which the apparatus located at each of the selected locations is passive.
A further object of this invention is to provide apparatus for remotely measuring at several selected locations on the surface of the earth the water status at those locations in which very little maintenance is required at the several selected locations.
Other objects and advantages of this invention will become apparent hereinafter in the specification and drawings.